In certain circumstances it is desirable to remove sections of tubular tissue structure from a patient's body. Such tissue may be used in another part of the patient's body, may be transplanted into a second patient's body or may be discarded. As used herein, the term “tubular tissue structure” includes blood vessels, tendons, bile ducts, nerves and any other similar tissue formation which is generally tubular in structure and capable of being separated from surrounding tissue. Although the invention herein will be discussed in terms of harvesting blood vessels it should be understood that the apparatus and method described are equally applicable to harvesting other solid or cylindrical tubular tissue structure.
Vein harvesting is commonly done in connection with coronary artery bypass surgery. The saphenous vein is a subcutaneous vein which is often used for coronary artery bypass grafting, infra-inguinal bypass grafting and vein—vein bypass grafting. Other vessels may also be used including the internal mammary artery, the radial artery, and/or the lesser saphenous vein. Previously, it has been necessary to make an incision along the full length of the vein section to be removed. The vein is then freed by severing and ligating the branches of the vein, after which the section of the vein can be removed from the patient. The full-length incision must then be closed, for example by suturing or stapling. Obviously, the harvesting of the vein in this manner leaves disfiguring scars which are cosmetically undesirable. Additionally, the large incision creates a risk of infection to the patient and may not heal properly, especially with those patients who have poor circulation in their extremities. Such an incision may create a chronic non-healing wound, requiring significant and costly medical treatment.
Devices for harvesting a section of a blood vessel without creating a full-length incision have been suggested and include that described in U.S. Pat. No. 4,793,346 (Mindich) and UK Patent No. GB 20 82 459A. These patents describe methods that use incisions at either end of the blood vessel to be harvested. Such devices and methods can be disadvantageous because greater blood loss than is necessary can result. These devices may also remove more tissue than is necessary because the size of the cutting device is not readily adaptable to the changes in the size of the blood vessel. In addition, these patents describe techniques which have a high probability of damaging the vessel, making it unsuitable for use as a vascular conduit.
In U.S. Pat. No. RE 36,043 (Knighton), a device and a method for vein removal are disclosed which solve some of the problems associated with the use of prior art devices. Knighton discloses an endoscope having a lumen extending longitudinally through the scope body. The endoscope includes means for viewing an area adjacent the distal end of the lumen. The lumen has a lateral dimension large enough to accommodate the blood vessel being harvested and at least one tool for use in harvesting the blood vessel. A first end of the blood vessel section to be harvested is exposed through an incision in the patient's body. A dissecting tool and a gripping tool are inserted through the lumen of the endoscope and used to dissect the blood vessel away from the surrounding connective tissue of the patient's body. Additional tools are provided for use through the lumen of the endoscope to remove body fluids and coagulate bleeding tissue, to ligate and sever side branches from the blood vessel to be harvested, and to ligate and sever a distal end of the blood vessel to be harvested when a desired length of blood vessel has been dissected. Only a small incision in the patient's body is necessary to harvest a relatively long length of blood vessel in a precise and controlled manner using this device and procedure.
U.S. Pat. No. 5,772,576 (Knighton et al.) also describes a device and method for vein removal. The device has one or more lumens extending through a body portion. One lumen is sized to accommodate a blood vessel and at least one tool for use in removing the vessel. The device may also include viewing means so that the operator may remotely view an area adjacent the distal end of the body portion. The device protects the vessel being removed from damage by the tools used in the procedure, which is critical since the blood vessel is destined for reuse (as in arterial bypass). In addition, a single operator can use the device.
In commonly assigned, co-pending application Ser. No. 09/715,665, (Knighton et al.) filed Nov. 17, 2000, entitled “Vein Harvesting System and Method”, the entirety of which is incorporated herein by reference, a system that is easier to use and minimizes damage to a blood vessel is described. In this system, a multi-lumen tube is used in conjunction with a housing having a removable lower portion. The housing provides a workspace for the removal of a blood vessel and the multi-lumen tube and associated tools provide a means to see and to remove a desired length of vein and cut and cauterize any vein side branches while minimizing damage to the vein and trauma to the patient. An additional problem with present technology is determining the course of the main saphenous trunk versus a large side branch. The course of the main vein would also be beneficial to see well ahead of the dissection to facilitate the speed of dissection.
The need also exists for a vein harvester having a variable length and further having tools that would be easier and more convenient to use. The tools typically used in the current procedures tend to be long and difficult to control. Having tools with a variable length would allow for an easier, more precise, and more rapid procedure.